first of all i dont know what you understand as new player so my view of a new player is that joined end2019/2020 so my arguments on based on that view
1 a new player can play showdown. (if a old player wanna play its up to him since he check the forums etc he is not that dead. they still like the game in a way)
2 i think most of the people pick know players that are active for example you umbra i think the chance someone pick me instead of you is 1%. so new player giving a chance is nice but a small percentage of that players gonna actually play.
3 what Gunthug said : To call PSL "an MMO event" is absolutely absurd and not true. PSL is a straight, unabashed rip-off of a Smogon event, which uses exclusively showdown tiers for its games ( i never played psl but adding a tier thats not mmo is not that bad since i tottaly agree with Gunthug )
4 i agree with the effort a old player and a new player put in this event so as coach it up to him if he want a good player that put less efort in a match or a new player that gonna give everything to win.
5 my english is bad xD